Reconfigurable Sensor Analog Front-End Using Low-Noise Chopper-Stabilized Delta-Sigma Capacitance-to-Digital Converter

Kim, Hyungseup; Lee, Byeoncheol; Mun, Yeongjin; Kim, Jae-Sung; Han, Kwonsang; Roh, Youngtaek; Song, Dongkyu; Huh, Seounghoon; Ko, Hyoungho

doi:10.3390/mi9070347

Cited by 9 publications

(8 citation statements)

References 31 publications

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“…If the method of increasing the signal power discussed in Section 3.1 is applied, there is room for reducing power consumption because the noise performance required to achieve the same SNR is alleviated [ 47 ]. Alternatively, a structure that removes the power of the pre-amplifier with a capacitance-to-digital (CDC) that connects the ADC directly to the sensor without using the pre-amplifier or a structure that eliminates overlapping circuits by combining the analog front-end pre-amplifier and ADC is suggested to reduce the power consumption of analog front-end circuits [ 48 , 49 , 50 , 51 , 52 ].…”

Section: Technical Issues Of the Capacitive Sensor Readout Systemmentioning

confidence: 99%

Readout Circuits for Capacitive Sensors

Yoo

Choi

2021

Micromachines

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The development of microelectromechanical system (MEMS) processes enables the integration of capacitive sensors into silicon integrated circuits. These sensors have been gaining considerable attention as a solution for mobile and internet of things (IoT) devices because of their low power consumption. In this study, we introduce the operating principle of representative capacitive sensors and discuss the major technical challenges, solutions, and future tasks for a capacitive readout system. The signal-to-noise ratio (SNR) is the most important performance parameter for a sensor system that measures changes in physical quantities; in addition, power consumption is another important factor because of the characteristics of mobile and IoT devices. Signal power degradation and noise, which degrade the SNR in the sensor readout system, are analyzed; circuit design approaches for degradation prevention are discussed. Further, we discuss the previous efforts and existing studies that focus on low power consumption. We present detailed circuit techniques and illustrate their effectiveness in suppressing signal power degradation and achieving lower noise levels via application to a design example of an actual MEMS microphone readout system.

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Section: Technical Issues Of the Capacitive Sensor Readout Systemmentioning

confidence: 99%

Readout Circuits for Capacitive Sensors

Yoo

Choi

2021

Micromachines

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“…The influences of the stray-capacitance of the cables need to be investigated. In some applications, the analysis of capacitive sensor noise [19][20][21][22][23] and the influences of stray-capacitance [24][25][26][27][28][29][30] have been considered in their experiments.…”

Section: Introductionmentioning

confidence: 99%

Investigation on Stray-Capacitance Influences of Coaxial Cables in Capacitive Transducers for a Space Inertial Sensor

Wang

et al. 2020

Sensors

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Ultra-sensitive inertial sensors are one of the key components in satellite Earth’s gravity field recovery missions and space gravitational wave detection missions. Low-noise capacitive position transducers are crucial to these missions to achieve the scientific goal. However, in actual engineering applications, the sensor head and electronics unit usually place separately in the satellite platform where a connecting cable is needed. In this paper, we focus on the stray-capacitance influences of coaxial cables which are used to connect the mechanical core and the electronics. Specially, for the capacitive transducer with a differential transformer bridge structure usually used in high-precision space inertial sensors, a connecting method of a coaxial cable between the transformer’s secondary winding and front-end circuit’s preamplifier is proposed to transmit the AC modulated analog voltage signal. The measurement and noise models including the stray-capacitance of the coaxial cable under this configuration is analyzed. A prototype system is set up to investigate the influences of the cables experimentally. Three different types and lengths of coaxial cables are chosen in our experiments to compare their performances. The analysis shows that the stray-capacitance will alter the circuit’s resonant frequency which could be adjusted by additional tuning capacitance, then under the optimal resonant condition, the output voltage noises of the preamplifier are measured and the sensitivity coefficients are also calibrated. Meanwhile, the stray-capacitance of the cables is estimated. Finally, the experimental results show that the noise level of this circuit with the selected cables could all achieve 1–2 × 10−7 pF/Hz1/2 at 0.1 Hz.

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“…For example, the circuit presented in [11,12] includes several high value resistors, capacitors, and a large number of active building blocks, which results in large chip area and very high power consumption. The solutions reported in [13,14,15,16,17,18,19] employ a large number of switches and require additional controlling clock signals. Moreover, the clock feedthrough and charge injection errors of switches limit their maximum achievable accuracy.…”

Section: Introductionmentioning

confidence: 99%

A VCII-Based Stray Insensitive Analog Interface for Differential Capacitance Sensors

Barile

Safari

Ferri

et al. 2019

Sensors

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In this paper, a novel approach to implement a stray insensitive CMOS interface for differential capacitive sensors is presented. The proposed circuit employs, for the first time, second-generation voltage conveyors (VCIIs) and produces an output voltage proportional to differential capacitor changes. Using VCIIs as active devices inherently allows the circuit to process the signal in the current domain, and hence, to benefit from its intrinsic advantages, such as high speed and simple implementation, while still being able to natively interface with voltage mode signal processing stages at necessity. The insensitiveness to the effects of parasitic capacitances is achieved through a simple feedback loop. In addition, the proposed circuit shows a very simple and switch-free structure (which can be used for both linear and hyperbolic sensors), improving its accuracy. The readout circuit was designed in a standard 0.35 μm CMOS technology under a supply voltage of ±1.65 V. Before the integrated circuit fabrication, to produce tangible proof of the effectiveness of the proposed architecture, a discrete version of the circuit was also prototyped using AD844 and LF411 to implement a discrete VCII. The achieved measurement results are in good agreement with theory and simulations, showing a constant sensitivity up to 412 mV/pF, a maximum linearity error of 1.9%FS, and acknowledging a good behavior with low baseline capacitive sensors (10 pF in the proposed measurements). A final table is also given to summarize the key specs of the proposed work comparing them to the available literature.

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Reconfigurable Sensor Analog Front-End Using Low-Noise Chopper-Stabilized Delta-Sigma Capacitance-to-Digital Converter

Cited by 9 publications

References 31 publications

Readout Circuits for Capacitive Sensors

Readout Circuits for Capacitive Sensors

Investigation on Stray-Capacitance Influences of Coaxial Cables in Capacitive Transducers for a Space Inertial Sensor

A VCII-Based Stray Insensitive Analog Interface for Differential Capacitance Sensors

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